Balancing means for fluid-pressure motors.



P. vHonerKINsoN.- BALANOING-MEANSOR FLUID PRESSURE MOTORS.

APPLICATION FILED SEPT. 1, 1909.

1,012,638. Patented Devz, 1911A 2 SHEETS-SHEET 1.

/f A Trou/Ey liv-mcg;

` F. HonGKINsoN.

BALANGING MEANS POR FLUID PRESSURE MOTORS.

' v APPEIOATION FILED SEPT. l, 1909. 1,01 2,638.

Patenteane, 26, A1911.

2 sunnita-SHEET 2.

2 lNVNTOR.

H/SA RNEYIN FACT.

FRANCIS HonGKINsoN, or nnenwoon PARK, PENNSYLVANIA, AssIGNoIz., BY. MnsNr.

ASSIGNMENTS, T0 THE COLONIAL TRUST COMPANY, TRUSTEE, OF PITTSBURGH,

PENNSYLVANIA, A. CORPORATION OE PENNSYLVANIA.

i BALANCING- MEANS FOR FLUID-PRESSURE MOTORS.

Speclieation of Letters Patent. v

Patented nee.' 2e, 1911.

Application med September 1, 1.909. Serial'No. 515,553.

To all whom 'it may concern:

Beit known that4 I', FRANCIS HooGKIN'soN a subject of the King of Great Britain and Ireland, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have made a new .and useful Invention in Balancing Means for Fluid- Pressure Motors, of which the following 'is a specification.

This invention relates to balancing means for fluid pressure motors. l

In certaintypes of fluid pressure motors and especially. in reaction turbines, it is necto provide balancing pistons to counterba ance thelongitudinal thrust exerted by the motive fluid (which, for convenience, will hereinafter bercalled steam) as it traverses the workingpassages of the turbine. Itis customary to divide theworking passagesv of such turbines into a convenient number of stages or sections of diffe-rent di ametersl and to provide aseparate balance piston for each stage or section. The balance pistons are mounted on the rotor` element'of the turbineand'a lateral face of each piston is exposed tothe pressure at the inlet end of the corresponding working stage or section. The pistons are so proportioned that thesteam exerts a, pressure on them equal and opposite to the longitudinal thrust encountered in the working stage. Labyrinth packings are provided between the turbine casing `and the balance pistons for ltl'1e"f'purpose of preventing steam from leaking'past the pistons. vThese -packings consist of a number of grooves or 'ridges formedon the peripheral face of the pistons and interleaving with oppositelydisposed grooves or ridges formed on `the inner face of the casin of the turbine. vIt is essen-V tial with suc a packing to keep the clearances particularly close and for this reason a small deflection of a balance piston will.y affect the operation of the turbine and is apt r to cause trouble.

An object of this a` ba.lance piston which is so constructed as to overcome difficulties heretofore vencountered and whichis simple in its construction and effective in'( p. .ratv1on1.

A further Objectis to produce -a-balancefv vention is to produce I I ugal iston in which theseparate parts are so ocated and so proportioned that the centrif- 'an enlarged sectional view of 'right angles to .'iange 15.

strains induced throughout the piston combine to produce a radial strain on the piston. v

A further object is to produce a balance s piston provided with means for equalizing the temperature strains in thepiston.

In the drawings accompanying this appli' cation and formlng a part thereof: Figure 1 is a transverse section of a turbine casing shown'in connection with a partial side and a partial sectional. elevation of the rotor eleand Fig. 2 is one end of the turbine and shows a section of a balance piston embod ing my invention.

The turlo7 ment in'place in the casing;

ine shown consists of rotor element 4 mounted'on shafts 5 and a stationary casing -6 which surrounds the element 4. The rotor element carries the moving blades and is constructed in diierent diameters to accommodate the different stages or sections.

The casing is correspondingly formed in sections of different diameters and 1t carries the stationary blades which coperateswith the moving blades of the rotor element.

The .turbine illustrated is divided into high, intermediate, and low pressure stages or sections. The anced by means of a balance piston 7 mounted on the rotor. The intermediate and low pressure working stages are balanced by a piston 9 mounted' on the rotor,and which discloses an embodiment of my invention. The hub portion 10 of the piston 9 is mounted on the rotor the rotor-and a ycompoun rin-g 11 consisting of an inner ring cut into segments and an outer ring shrunkonto the inner ring and which holds the segments of the inner ring "in pl ce. in a groove provided for them in the rotor elementd A The piston 9 consists of the hub ortion 10, .a short web 12, formed integral y with the' hub portion', nular a'nge 13, and ally with the flange v the inge tsouterjor peripheral ledge with an annular Labyrinth packings of the ordinary con.- struction are vprovided between the peripheral faces of the anges high pressure stage is ball 13 and 15 and the a laterally projectlng ana web 14 formed coaxi-v 13 but which is turned at,l

and is provided at and the chamber 18 communicates with the exhaust passage of the'turbine through the pipe 21. The packing betweensthe flange 1'3 andthe casing separates the 'chambers 16 and 17 and the packing between the flange 15 and the' casing separates the chambers 17 and 18. These packings are maintained by close lateral adjustment` of the rotor element and consequently it is essential that the piston 9 does not distort and therebyi destroy t1 e close lateral adjustment. The tendency of the piston to distort, under the influence of the centrifugal strains, is overcome by they construction.

The flanges 13 and 15 are so constructed,

proportioned and located that the centrifugal stresses combine to produce a radial strain on the piston. The centrifugal stresses induced 1n the flange l13 tend to cause a deiection or distortion of the piston vn one direction. This distorting tendency 1s counteracted by the centrifugal stresses induced in the flange l5 which tend to cause a distortion of the iston'in theopposite direction. The resultant of the centrifugal strains on the'web 12 are radial and, therefore, there is no tendency for the piston to distort. A

The piston 9 vis exposed on one side to exhaust pressure through the pipe 21 and to intermediate and low. pressure steam on the other side. The bers 16 and 17 correspond respectively to the temperatures of steam at a pressure corresponding to the ressure in the chamber and vare hlgher than t e temperature of the chamber 18 which corresponds to the temperature of steam at exhaust pressure; Vconsequently there is a tendency for the webs 12 and 14 to expand unequally on opposite sides and to cause a lateral distortion of the piston. I overcome this, illustrated, by securing a plate 22- to the low pressure end .of the rotor element 5 and to ,the flange 15 so-asto segregate a portion 2 3 1 of the low pressure chamber, between the piston 9 and the plate 22'. This plate 22 isv provided with an annular row of openings 24 located near.its outer periphery so that ample communication is had between the Achamber 18 andthe segregated portion 23.

The pressure in' the chamber 23 isthe Vsame as the pressure in the chamber 18, but the temperatures of the chamin the apparatus 'the piston to distort, due to unequal temperature strains, will be substantially overcome.

I find it advisable to provide the openings 24 near the outer edge of the plate, for the reason that the moist and heavy steam or the air contained in the chamber 23 is moved by the centrifugal force to the outer portion of the chamber 23 and is then discharged into the chamber 18 through the opening 24. The chamber 23 is then filled with dry and superheated steam which is a relatively poor conductor of heat and consequently assists in maintaining the temperature of thechamber 23 about equal to the temperature of the chambers 16 and 17. Another advantage in the shaftl 5 and the casing of the turbine, is not evaporated upon coming in contact with the plate 22 but is discharged into the exhaust with the steam or water leaking past the interleaving seal, located between the A `flange 15 and the casing. If the plate were not provided, such liqlud upon leaking into the chamber 18 would come in contact with the web 14 of the balance piston and be evaporated by the high temperature of the web and deposit a. sediment on the piston. This sediment by falling o the piston in spots would tend to unbalance the piston and to detrimentally affect the operation of the turbine. y

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the a paratus-which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out What I claim is: Y

l. In a fluid pressure motor, a balance piston exposed to different pressures of motive fluid on opposite sides av ture equalizing plate, said piston and openings located edge.

2. In a fluid pressure motor,

located l011 one side of provided with a row of a ong the outer peripheral a balance pis- `ton exposed on opposite sides to different pressures and provided with an equalizing chamber and means communicating with said chamber for discharging the moist and heavy fluid therefrom.

3. In a fluid pressure motor, a balance piston provided with anges so located that the centrifugal pressure induced in one flange combines with the centrifugal forces by other means.l

d a temperal induced in another iange to produce a radial strain in said piston.

4. In a fluid pressure motor, a balance piston provided with flanges so located that the centrifugal stressesV induced in said flanges combine to produce radial strains in said piston.

5. In a iuid pressure motor, a balance piston comprising `separate portions so located that the centrifugal stresses induced in one ortion combine with the centrifugal stresses 1n another portion to produce radial strains,

,- "a temperature equalizing chamber located on one side of sald piston and means communicating therewith for discharging heavy and moist Huid therefrom.

6. In a fluid pressure motor, a balance piston exposed on opposite sides to different pressures and comprising separate portions so located that the centrifugal strains-induced in one portion combine with the centrifugal strains in another portion to produce radial strains anda temperature equal-v izing' chamber located within said piston.

7 In a fluid pressure turbine, a balance piston exposed on one side to the same pressure as a working. stage of said turbine and on the other side to exhaust pressure, and temperature equalizing means located on the exhaust side and provided with means for discharging Huid therefrom.

8. In a fluid pressure motor, a flanged balance piston` exposed on op site sides to different pressures of motive uid and means secured to the flange of said piston for causing substantial equalization of the temperature strains in said iston.

In testimony whereo I have hereunto subscribed my name this 26th day of August,

FRANCIS I-IODGKINSON.

Witnesses:

v C. W. MCGBEE,

WM. I-I. LARIMEB. 

